The present invention relates to an airtight container using a cover unit having an airtight unit and an extended unit and a packing unit of a flexible material. The airtight container comprises: a container main body; a cover unit connected to one side of the container main body; and a packing unit inserted inside the container main body. In addition, the packing unit of which at least one side breaks away from a shape of a lower end circumference in the cover unit is formed.
